Insect control has been a desired goal of mankind throughout history. Early attempts at control involved placing sticky substances at locations where insects would be required to pass. Such attempts are believed to have lead to the development of the product which came to be known as "fly paper" which is merely a strip of material covered with a sticky substance. Such a product is described in U.S. Pat. No. 813,116 issued in 1906 to Julius H. Bien.
Another method of controlling insects involved catching them in traps which may include an attractant and a tacky substance. Such traps have become more and more sophisticated and complex. For example, see U.S. Pat. No. 3,755,958.
A common present-day means for controlling insects involves application of insect control agents either by vaporization or by application to a suitable carrier strip or device. Vaporization may be accomplished by the use of conventional aerosol dispensers or by means of plastic strips which exude vapors of the insect control agent. Vaporization by the former technique has its disadvantages in that there is very little control over the dispersal of the control agent so that it may spread into areas where it is not wanted. Additionally, this technique does not provide for sustained insect control. Vaporization by the latter technique has its disadvantages in that the insect control agent either does not firmly adhere to the plastic strips or the plastic strips are not resistant to environmental degradation. In the former situation the agent may be readily dislodged from the substrate by environmental causes such as wind or rain. In the latter situation the substrates have short useful lives. In both situations the resulting devices do not provide sustained release of the insect control agent under outside environmental conditions.
Various techniques have been suggested for providing sustained release of insect control agents. For example, U.S. Pat. No. 4,056,610 discloses a microcapsule insecticide composition in which a pyrethroid permeates a porous shell wall and maintains an insecticidally effective level of the pyrethroid upon the outer surface of the shell wall for an extended period of time. Control is achieved by killing insects which contact the pyrethroid released through the capsule wall. For this purpose, the capsules are spread about in various ways with the purpose of contacting insects. Although this patent mentions incorporating microcapsules in sheet materials such as tapes, the present invention provides an improvement thereover.
U.S. Pat. No. 4,103,450 discloses the use of insecticide materials on the surface of a low density web of synthetic fibers. These devices are installed so that they will create a lethal zone for the insect to pass through and be exposed to the insecticide. These devices are useful for certain purposes but they suffer from the disadvantage that they do not stand up well to the rigors of outside environmental conditions.